What's a good iOS game to keep my mind sharp while I'm stuck on a job site waiting for concrete to dry?

Look, I ain't gonna lie, I'm not usually one for these 'Bible' games, but this Bible Crossword Game actually gets the job done. Keeps your mind from turning to mush when you're stuck waiting around. It's got a ton of different puzzles, and they're actually pretty challenging. It ain't built like a brick house visually, but it works, even with gloves on. The battery drain ain't too bad either, which is a plus when you're out in the field all day. The tutorial's useless, no BS, but once you figure it out, it's straightforward. Just download it and give it a shot. Beats staring at wet concrete all day, that's for sure. Plus, the wife seems to like it too, so that's a win-win.